Modeling biomass particle pyrolysis with temperature-dependent heat of reactions

Haseli, Yousef; Oijen, van Ja Jeroen; Goey, de Lph Philip

doi:10.1016/j.jaap.2010.11.006

Cited by 99 publications

(57 citation statements)

References 35 publications

(113 reference statements)

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“…Such methods lead to varying estimates ranging from endothermic to exothermic (see Table 1). One issue which contributes to the these discrepancies was originally highlighted by (Kung and Kalelkar, 1973) -and recently corroborated by (Haseli et al, 2011) -is related to whether the temperature-dependence of the heat of pyrolysis are accounted for in the single particle models. Based on the fitting, they concluded that the standard enthalpy of pyrolysis (at a reference temperature) is endothermic (25 kJ/kg); however, at elevated temperatures, the enthalpy of pyrolysis can be exothermic (due to differences in the heat capacities of products and reactants).…”

Section: Previous Estimates For the Heat Of Pyrolysismentioning

confidence: 98%

“…The temperature and composition dependent specific heat capacities (J kg -1 K -1 ) of the solid pseudo components were modeled according to (Merrick, 1983): (10) where R is the ideal gas constant 8.314 J mol -1 K -1 and the average molecular weight of the solid pseudo component X (A,B,C) is calculated from its respective elemental composition,…”

Section: Specific Heat Capacitymentioning

confidence: 99%

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Biomass torrefaction: Modeling of reaction thermochemistry

Bates

Ghoniem

2013

Bioresource Technology

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ABSTRACT:Based on the evolution of volatile and solid products predicted by a previous model for torrefaction (Bates and Ghoniem, 2012) a model has been developed which describes their thermal, chemical, and physical properties as well as the rates of heat release. The first stage of torrefaction, associated with hemicellulose decomposition, is exothermic releasing between 40-280 kJ/kg initial . The second stage is associated with the decomposition of the remaining lignocellulosic components, completes over a longer period, and is predicted to be either endothermic or exothermic depending on the temperature. Increasing torrefaction severity, as quantified by the mass loss, is predicted to cause greater heat release. The rate of mass loss and rate of heat release increase with higher temperatures. The higher heating value of volatiles produced during torrefaction was estimated to be between 4.4 and 16 MJ kg -1 increasing with the level of mass loss. Highlights: Model developed to describe the energy balance during willow torrefaction  First stage is exothermic releasing 40-280 kJ/kg  Second stage is either exothermic or endothermic  Higher torrefaction temperatures result in increased reaction rate and heat release rate

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Section: Previous Estimates For the Heat Of Pyrolysismentioning

confidence: 98%

Section: Specific Heat Capacitymentioning

confidence: 99%

Biomass torrefaction: Modeling of reaction thermochemistry

Bates

Ghoniem

2013

Bioresource Technology

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“…They further proposed that vapor tar might undergo secondary reactions in terms of tar cracking reactions yielding additional light gases and char. There exist experimental evidences for both groups of primary and secondary reactions; which have been addressed by Haseli et al [12]. However, it is less likely that tar would experience carking reactions inside the particle due to short residence time of volatiles released during the pyrolysis process.…”

Section: Figmentioning

confidence: 99%

“…The common conclusion from these works was that the char yield was the main factor determining whether the overall pyroysis process is endothermic or exothermic. A survey on the wide range of heat of pyrolysis has been conducted in a recent study by Haseli et al [12].…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the conversion time of single pyrolyzing biomass particles at high heating conditions

Haseli

Oijen

Goey

2011

Chemical Engineering Journal

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“…When one fifth of species standard state enthalpy, namely total enthalpy, 965.6 kJ/kg is adopted, reasonable results can be obtained. However, this enthalpy value is slightly higher than the values obtained by other researchers [31] [32]. The species standard state enthalpy used in this numerical analysis is only for the decomposition of volatile gas, while other researchers' data may be for the total pyrolysis process of solid wood pieces, which includes exothermic reaction of char formation.…”

Section: Endothermic Reactionmentioning

confidence: 59%

Numerical Analysis on Wood Pyrolysis in Pre-Vacuum Chamber

Homma¹,

Homma²,

Idris³

2014

JSBS

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In the previous experimental work, a new technology system for wood pyrolysis was developed to aim at mitigating climate change, global warming, and energy crisis as well as enhancing low electrification in rural areas in developing countries. The new technology system equipped with a pre-vacuum chamber requires low cost and less maintenance. However, large wood pyrolysis in the pre-vacuum chamber is rather complicated. To obtain a good understanding of the previous experimental results, a numerical analysis taking account of heat-mass transfer and chemical reaction is carried out. Two-step general reaction model is proposed for the numerical analysis. The first stage is volatile and char formation from the wood pieces and the second state is decomposition of the volatile to five species including vapor of tar. In this analysis, chemical formulae of the volatile and the tar are successfully identified hypothetically. The results obtained by this numerical analysis can explain the experimental results reasonably and provide useful information about time evolution of volatile formation, temperature change in pre-vacuum chamber with time, and species mole concentration decomposed from the volatile.

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Modeling biomass particle pyrolysis with temperature-dependent heat of reactions

Cited by 99 publications

References 35 publications

Biomass torrefaction: Modeling of reaction thermochemistry

Biomass torrefaction: Modeling of reaction thermochemistry

Numerical study of the conversion time of single pyrolyzing biomass particles at high heating conditions

Numerical Analysis on Wood Pyrolysis in Pre-Vacuum Chamber

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